Grammar fix

Author: ncoghlan

Doc/whatsnew/3.13.rst

@@ -1655,7 +1655,7 @@ optparse
   While :mod:`argparse` remains preferred for new projects that
   aren't using a third party command line argument processing
   library, there are aspects of the way ``argparse`` works that
-  means the lower level ``optparse`` module may provide a better
+  mean the lower level ``optparse`` module may provide a better
   foundation for *writing* argument processing libraries.
   (Contributed by Alyssa Coghlan in :gh:`126225`.)